1. Technical Field
The exemplary disclosure generally relates to control circuits, and particularly to a power control circuit and a loop analyzing apparatus comprising the power control circuit.
2. Description of Related Art
A loop analyzer is used to obtain a Bode plot of a power supply circuit to test stability of the power supply circuit. The power supply circuit, such as a buck converter for example, works in different modes according to different loads on the circuit. For example, the power supply circuit operates in a discontinuous conduction mode (DCM) when the power supply circuit drives a light load. In the DCM, current through an inductor of the power supply circuit falls to zero during part of a charging and discharging cycle (that is, a commutation cycle) of the inductor. The power supply circuit operates in a continuous conduction mode (CCM) when the power supply circuit drives a heavy load. In the CCM, a current through an inductor of the power supply circuit never falls to zero during the commutation cycle of the inductor.
Since the current through the inductor of the power supply circuit falls to zero during part of the commutation cycle when the power supply circuit operates in the DCM, feedback signals output from the power supply circuit in response to testing signals from the loop analyzer are discontinuous. The loop analyzer may thus not be able to obtain a correct Bode plot of the power supply circuit when the power supply circuit drives a light load because of the discontinuous feedback signals.
Therefore, there is room for improvement within the art.